/Engine/Source/Runtime/MovieScene/Public/EntitySystem/MovieSceneInitialValueCache.h
Retrieve the extension ID for this structure when added to aUMovieSceneEntitySystemLinker
static [TEntitySystemLinkerExtensionID](API\Runtime\MovieScene\EntitySystem\TEntitySystemLinkerExtensionID)< [FInitialValueCache](API\Runtime\MovieScene\EntitySystem\FInitialValueCache) > GetExtensionID()